The present invention relates to a paper feed suction apparatus in a sheet-fed press or the like, which draws each paper sheet stacked on a paper stack table or the like from the highest one and supplies it to the latter feed stage.
In a sheet-fed press or folding machine, a paper feed suction apparatus called a sucker apparatus is provided to a paper feed apparatus for supplying the paper sheets to a printing press. The sucker apparatus draws the paper sheets stacked on the paper stack table or the like one by one from the highest one and supplies them to the latter stage such as a paper feed roller of the paper feed apparatus.
A conventional sucker apparatus used as the paper feed suction apparatus of this type comprises a first suction port mechanism of a triple structure and a second suction port mechanism, both of which are supported on a sucker frame side, as disclosed in Japanese Patent Laid-Open No. Sho 57-145741 (corresponding to Japanese Patent Publication No. 1-34903 and U.S. Pat. No. 4,438,916).
More specifically, the first suction port mechanism has the triple structure constituted by a cylindrical guide nozzle, a cylindrical intermediate nozzle, and a cylindrical suction port member. The guide nozzle is supported by the sucker frame and connected to a suction air source. The intermediate nozzle is fitted on the lower small-diameter portion of the guide nozzle to be vertically movable and biased downward by an outer spring. The suction port member is fitted on the outer circumference of the intermediate nozzle to be vertically movable and biased downward by an inner spring. A suction hole is formed in the lower end portion of the suction port member, so that the inner hole of the suction port member communicates with the outside.
With this arrangement, when a printing operation is to be started, the intermediate nozzle and the suction port member are located below by a cam mechanism, and the lower end face of the suction port member is close to the upper end face of the stacked paper sheets. In this state, when a feeding operation is started, and an air suction is performed, the uppermost paper sheet is drawn to its lower end face by the suction hole of the suction port member. Since the suction hole is closed by the paper sheet, a continuous air suction causes a change in pressure inside the suction port member, the intermediate nozzle, and the guide nozzle to a negative pressure with respect to an atmospheric pressure. The inner spring is compressed by the atmospheric pressure to move the suction port member upward with the paper sheet being chucked on the lower end face.
When the collar of the suction port member abuts against the collar of the intermediate nozzle, the upward movement of the suction port member is temporarily stopped. At the same time, the intermediate nozzle is moved upward by the cam mechanism, so that the suction port member and the intermediate nozzle are moved upward together while compressing the outer and inner springs. At the upper limit, the suction air acts on the second suction port mechanism, and the supply of the suction air to the first suction port mechanism is stopped. The paper sheet is transferred from the first suction port mechanism to the second suction port mechanism. The second suction port mechanism moves forward to cause the paper feed roller of the latter feed stage to grip the paper sheet.
In the above-described conventional paper feed suction apparatus, however, the first suction port mechanism has the triple structure, which causes an increase in number of components and weight. In addition, since the cam mechanism forces the intermediate nozzle to move in the vertical direction, a distortion is generated between the intermediate nozzle and the guide nozzle. Hence, a paper feed error tends to occur.
In order to solve the above problem, the present applicant has proposed a paper feed suction apparatus disclosed in Japanese Utility Model Publication No. 3-24511. This apparatus will be described below with reference to FIGS. 3 and 4. FIG. 3 shows a paper feed suction apparatus, and FIG. 4 shows a first suction port mechanism.
Referring to FIGS. 3 and 4, a sucker frame 2 is disposed above paper sheets 1 stacked on a paper stack table through a paper stack plate. The sucker frame 2 projects backward from the upper end portion of a paper feed frame. A cam 3 is axially mounted on a shaft axially supported by the sucker frame 2. A pair of left and right first suction port mechanisms 4 are provided to the lower end portion of the sucker frame 2. The first suction port mechanisms 4 are supported by U-shaped holders 5 projecting from the sucker frame 2. A pair of left and right second suction port mechanisms (neither are shown) connected to an air source are disposed in front of the first suction port mechanisms 4 in correspondence with each other.
Each first suction port mechanism 4 comprises a cylindrical guide nozzle 7 swingably supported on the corresponding holder 5 by a pin 6 and having the inner hole connected to the air source. A controller (not shown) coupled to the upper U-shaped portion of each guide nozzle 7 controls the gradient of the whole first suction port mechanism 4.
Reference numeral 8 denotes a suction port member having a bottomed-cylindrical shape and fitted on the outer circumferential surface of the guide nozzle 7 to be vertically movable. A plurality of suction holes 8a are formed in the lower end face of the suction port member 8. The suction port member 8 is biased downward by a suction port spring 9 interposed between the lower-end step portion of the inner hole and the step portion of the guide nozzle 7. When one end of a collar 8b of the suction port member 8 is brought into slidable contact with a guide 10 stationarily suspending from the holder 5, the pivotal movement of the suction port member 8 is regulated.
A roller lever 12 and an arm 13 are integratedly formed in an L-shaped form and axially mounted on the central portion of an arm shaft 11 pivotally axially supported between the left and right sucker frame 2. A cam follower 14 pivotally mounted on the roller lever 12 opposes the cam 3 having a cam surface comprising large- and small-diameter portions. Reference numeral 15 denotes a tension spring for applying a biasing force to the arm 13 in a direction to press the cam follower 14 against the cam surface of the cam 3.
The central portion of a guide bar 16 which horizontally extends in parallel to the arm shaft 11 is fixed and supported on the free end portion of the arm 13 by split clamping. A holder 17 is fixed at each end portion of the guide bar 16 by split clamping. An upper stopper shaft 18 is fixed on the upper end portion of the holder 17 by split clamping. An upper stopper 19 is located above the collar 8b and pivotally fitted on the distal end portion of the upper stopper shaft 18.
A lower stopper shaft 20 is fixed on the lower end portion of the holder 17 in parallel to the upper stopper shaft 18. A lower stopper 21 is located under the collar 8b and pivotally fitted on the distal end portion of the lower stopper shaft 20. With this arrangement, when the suction port member 8 abuts against the upper or lower stopper 19 or 21, the upward or downward movement of the suction port member 8 is regulated.
In the above arrangement, a printing operation is started in a state in which the suction port members 8 are moved downward, supported by the lower stoppers 21, and stopped while keeping the lower end faces close to the paper sheet 1. When suction air acts on the first suction port mechanisms 4, the uppermost paper 25 sheet 1 is chucked on the lower end faces of the suction port members 8. The suction holes 8a of the suction port members 8 are closed by the paper sheet 1 to cause a change in pressure inside the inner holes of the suction port members 8 and the guide nozzles 7 to a negative pressure. The pressure difference between the internal and the external pressures moves the suction port members 8 upward together with the paper sheet 1 against the biasing forces of the suction port springs 9.
When the collars 8b abut against the upper stoppers 19, the suction port members 8 are temporarily stopped. At this time, the contact portion between the rotating cam 3 and the cam follower 14 is shifted from the large-diameter portion to the small-diameter portion. The holders 17 are moved upward through the swingable movement of the arm 13, and the upper stoppers 19 are moved upward to escape from the collars 8b. At the same time, the suction port members 8 follow the upper stoppers 19 to be moved upward. At the upper limit, the supply of the suction air to the first suction port mechanisms 4 is stopped, and the suction air acts on the second suction port mechanisms. The paper sheet 1 is transferred from the first suction port mechanisms 4 to the second suction port mechanisms and conveyed for feeding.
At the upper limit where the suction port members 8 moved upward by the suction air are stopped, the cam follower 14 completely reaches the small-diameter portion of the cam 3. At this time, however, the lower stoppers 21 are not in contact with the collars 8b. Hence, after the paper sheet 1 is transferred, the pressure inside the suction port members 8 becomes almost equal to the atmospheric pressure, so that the suction port members 8 are moved downward by the biasing forces of the suction port springs 9 and temporarily stopped when the collars 8b abut against the lower stoppers 21. At this time, the contact portion between the cam 3 and the cam follower 14 is shifted from the small-diameter portion to the large-diameter portion. The lower stoppers 21 are moved downward through the swingable movement of the arm 13, and the suction port members 8 follow the lower stoppers 21 to be moved downward.
The lower stoppers 21 support the collars 8b of the suction port members 8 at the lower boundary and stop the suction port members 8 at a predetermined distance from the paper sheet 1. The suction port members 8 are quickly moved upward with the paper sheet 1 being chucked thereon, abut against the upper stoppers 19, and thus temporarily stopped. In this case, the suction port members 8 are moved upward by a smaller ascending amount than that of continuous ascending without any stop. In addition, an impact acting when the suction port members 8 abut against the upper stoppers 19 makes it possible to reliably separate the chucked paper sheet 1 from the second paper sheet.
In the conventional paper feed suction apparatus, however, the weights of the suction port members 8 are increased. Follow-up performance in a high-speed operation is degraded. As a result, the contact timing between the collars 8b of the suction port members 8 and the upper stoppers 19 is lagged. Therefore, it may be impossible to temporarily stop the suction port members 8.
More specifically, after the collars 8b abut against the upper stoppers 19 to stop the suction port members 8, the arm 13 and the suction port members 8 are moved together by the operation of the cam 3. If this timing is lagged, the arm 13 is moved before the collars 8b of the suction port members 8 abut against the upper stoppers 19. In this case, the timing of a temporary stop required to eliminate the operation lag between the left and right suction port members 8 operated by the suction air may be lagged or lost.